The present invention relates to motion control systems and, more specifically, to mover systems with identification schemes to provide identification of movers and their sequences on a track.
Mover systems utilizing linear drives can be used in a wide variety of processes (e.g. packaging, assembly automation, processes involving use of machine tools, etc.) and provide an advantage over conventional conveyor belt systems to provide flexible, extremely high speed movement, and mechanical simplicity. The mover systems provide a set of independently moveable “movers” supported on a track that holds individually controllable electric coils. Successive activation of the coils by drive electronics and a control system create a magnetic field that moves and relocates the movers along the track. Sensors may be spaced at fixed positions along the track and/or on the movers to provide information about the position and speed of the movers.
More specifically, magnetic sensors allow the movement of the movers to be detected with extreme accuracy providing submillimeter positioning. For example, by detecting the presence and effect of externally applied magnets attached to the movers, the magnetic sensors can detect the location of a mover and use it with a feedback control system to provide independent movement and positioning of each mover on the track.
In many applications, the movers provide packaging and materials handling of diverse objects along unique paths to highly specific positions along the track. Different sizes of mover frames (e.g., small, medium, and large frames) help to accommodate the different load sizes. The objects of each load, the size of each mover frame, and the order of the movers are prearranged so that each mover travels a particular path with respect to other movers on the track. When movers are installed and uninstalled onto the track, for example, for routine maintenance or repair, it is desired to discern the position and order of each mover before operation resumes. For example, if the person conducting maintenance or repair replaces the mover in the wrong position, the unique sequence of movers will be incorrect and will need to be corrected for operation.
One mode of identifying movers is the use of radio frequency identification (RFID) which detects RFID tags on the movers as the movers pass through a RFID reader positioned on or near the track. In this method, an application program will typically provide a system start-up operation which moves the movers along the track so that each mover passes near the RFID reader. Each mover is installed with a unique tag carrying electronically stored information such as a unique multi-bit serial number associated with each mover. The tag will transmit an identifying signal that is read by the RFID reader so that the identity of the mover can be determined. Use of RFID in product delivery systems is described in U.S. Pat. No. 7,931,197, entitled “RFID-based product manufacturing and lifecycle management,” assigned to the present applicant, and hereby incorporated by reference.
The use of RFID tags and readers requires unique identifying information to be installed on each mover and a database of identifying information to be stored in a system database. Also each mover must pass in close proximity to a RFID reader so that the RFID tags can be read. This process can be time consuming and intrusive, especially when resuming mover operations already in process.